Air conditioner

ABSTRACT

An air conditioner executes a heating operation using at least a high pressure refrigerant, and includes a refrigerant circuit configured to execute a vapor compression refrigeration cycle. The refrigerant circuit includes a convective heat exchanger, a radiant heat exchanger, an open/close valve and a check valve. The convective heat exchanger executes heat exchange between the high pressure refrigerant flowing inside and an air flowing towards outside. The radiant heat exchanger heats a predetermined member using the high pressure refrigerant flowing inside to cause the predetermined member to emit a radiant heat. The open/close valve is disposed upstream of the radiant heat exchanger in order to block a flow path of the high pressure refrigerant flowing towards the radiant heat exchanger during the heating operation. The check valve is disposed between the radiant heat exchanger and the open/close valve.

TECHNICAL FIELD

The present invention relates to an air conditioner including a refrigerant circuit configured to execute a vapor compression refrigeration cycle.

BACKGROUND ART

Patent Literature 1 (Japan Laid-open Patent Application Publication No. JP-A-H07-055234) describes an exemplary air conditioner configured to execute a heating operation using a high pressure refrigerant. Specifically, the exemplary air conditioner is configured to cause the high pressure refrigerant to flow into a radiant heat exchanger. In the exemplary air conditioner described in Patent Literature 1 (Japan Laid-open Patent Application Publication No. JP-A-H07-055234), a valve is disposed on the downstream of the radiant heat exchanger for regulating the amount of the high pressure refrigerant flowing into the radiant heat exchanger during a heating operation. The valve is configured to close the flow path for preventing the high pressure refrigerant from flowing into the radiant heat exchanger when the temperature of the radiant heat exchanger is increased to the upper limit.

SUMMARY OF THE INVENTION Technical Problem

In the aforementioned structure, however, the high pressure refrigerant is trapped in the radiant heat exchanger by means of the pressure of a compressor. Accordingly, the refrigerant, a compressor oil and etc. reside in the radiant heat exchanger. This makes it difficult to lower the temperature of the refrigerant. In other words, the temperature of the radiant heat exchanger cannot be lowered when necessary. Further, the amount of the compressor oil to be returned to the compressor is reduced. Therefore, chances will be increased that reliability of the compressor is deteriorated.

In view of the above, the applicant of the present invention produced a structure for preventing the high pressure refrigerant from being trapped in the radiant heat exchanger. Specifically in the structure, an open/close valve is disposed on the upstream of the radiant heat exchanger for blocking the flow path of the high pressure refrigerant flowing towards the radiant heat exchanger. Even in the structure, the refrigerant is changed into liquid in the radiant heat exchanger during a heating operation and resides in the vicinity of the radiant heat exchanger and the open/close valve. When the liquid refrigerant spontaneously evaporates under the condition and the internal pressure is increased, the open/close valve is pushed and repeatedly opened and closed by means of the increased internal pressure. This phenomenon is so-called “chattering”.

It is an object of the present invention to provide an air conditioner preventing occurrence of chattering in an open/close valve even when a refrigerant is changed into liquid in a radiant heat exchanger and resides in the vicinity of the radiant heat exchanger and the open/close valve during a heating operation.

Solution to Problem

An air conditioner according to a first aspect of the present invention includes a refrigerant circuit configured to execute a vapor compression refrigeration cycle and is configured to execute a heating operation using at least a high pressure refrigerant. In the air conditioner, the refrigerant circuit includes a convective heat exchanger, a radiant heat exchanger, an open/close valve and a check valve. The convective heat exchanger is configured to execute heat exchange between the high pressure refrigerant flowing through the inside thereof and an air flowing towards the outside thereof. The radiant heat exchanger is configured to heat a predetermined member by means of the high pressure refrigerant flowing through the inside thereof for causing the predetermined member to emit a radiant heat. The open/close valve is disposed on the upstream of the radiant heat exchanger for blocking a flow path of the high pressure refrigerant flowing towards the radiant heat exchanger during the heating operation. The check valve is disposed between the radiant heat exchanger and the open/close valve.

According to the air conditioner of the first aspect of the present invention, the check valve is disposed between the radiant heat exchanger and the open/close valve. When the open/close valve is closed, less liquid refrigerant exists between the open/close valve and the check valve. Even when the liquid refrigerant spontaneously evaporates and the internal pressure is increased, the internal pressure is not increased enough to push and open the open/close valve. Occurrence of chattering is thereby prevented.

An air conditioner according to a second aspect of the present invention relates to the air conditioner according to the first aspect of the present invention. In the air conditioner, the open/close valve is an opening degree regulating valve having a function of blocking the flow path and a function of regulating an opening degree of the flow path.

According to the air conditioner of the second aspect of the present invention, performance of the radiant heat exchanger is increased or reduced by regulating the opening degree of the refrigerant flow path. Further, the refrigerant flow path is configured to be blocked when the performance of the radiant heat exchanger reaches a predetermined set value. Convenience and security of the air conditioner can be thereby enhanced.

An air conditioner according to a third aspect of the present invention relates to the air conditioner according to one of the first and second aspects of the present invention. In the air conditioner, the open/close valve is configured to block the flow path when a temperature of the predetermined member reaches an upper limit of a permissive temperature.

According to the air conditioner of the third aspect of the present invention, the high pressure refrigerant is prevented from flowing into the radiant heat exchanger when the temperature of the predetermined member of the radiant heat exchanger reaches the upper limit of the permissive temperature thereof during execution of a heating operation using the radiant heat exchanger. Therefore, reduction in the temperature of the refrigerant is accelerated within the radiant heat exchanger. As a result, reduction in the temperature of the predetermined member is accelerated and the air conditioner can be returned to the heating operation using the radiant heat exchanger.

Advantageous Effects of Invention

According to the air conditioner of the first aspect of the present invention, less liquid refrigerant exists between the open/close valve and the check valve. Even when the liquid refrigerant spontaneously evaporates and the internal pressure is increased, the internal pressure is not increased enough to push and open the open/close valve. Occurrence of chattering is thereby prevented.

According to the air conditioner of the second aspect of the present invention, performance of the radiant heat exchanger is increased or reduced by regulating the opening degree of the refrigerant flow path. Further, the refrigerant flow path is configured to be blocked when the performance of the radiant heat exchanger reaches a predetermined set value. Convenience and security of the air conditioner can be thereby enhanced.

According to the air conditioner of the third aspect of the present invention, the high pressure refrigerant is prevented from flowing into the radiant heat exchanger when the temperature of the predetermined member of the radiant heat exchanger reaches the upper limit of the permissive temperature thereof during execution of a heating operation using the radiant heat exchanger. Therefore, reduction in the temperature of the refrigerant is accelerated within the radiant heat exchanger. As a result, reduction in the temperature of the predetermined member is accelerated and the air conditioner can be returned to the heating operation using the radiant heat exchanger.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a refrigerant circuit diagram of an air conditioner according to an exemplary embodiment of the present invention.

FIG. 2 is an exploded perspective view of the internal structure of an indoor unit.

FIG. 3 is a side view of a heat exchanger assembly.

FIG. 4 is a cross-sectional view of a radiant heat exchanger, illustrating an exemplary attachment structure of a panel and heat transfer tubes.

FIG. 5 is a chart representing the relation between temperature to be detected by a second temperature sensor and actions of an open/close valve during a heating operation.

FIG. 6 is a cross-sectional view of the radiant heat exchanger, illustrating a second attachment structure of the panel and the heat transfer tubes.

FIG. 7 is a cross-sectional view of the radiant heat exchanger, illustrating a third attachment structure of the panel and the heat transfer tubes.

FIG. 8 is a cross-sectional view of the radiant heat exchanger, illustrating a fourth attachment structure of the panel and the heat transfer tubes.

FIG. 9 is a cross-sectional view of the radiant heat exchanger, illustrating a fifth attachment structure of the panel and the heat transfer tubes.

FIG. 10 is a cross-sectional view of the radiant heat exchanger, illustrating a sixth attachment structure of the panel and the heat transfer tubes.

DESCRIPTION OF EMBODIMENTS

An exemplary embodiment of the present invention will be hereinafter explained with reference to figures. It should be noted that the following exemplary embodiment is merely a specific example of the present invention, and therefore does not intend to limit the technical scope of the present invention.

<Refrigerant Circuit 10 for Air Conditioner 1>

FIG. 1 is a refrigerant circuit diagram of an air conditioner according to the exemplary embodiment of the present invention. As illustrated in FIG. 1, the air conditioner 1 includes an indoor unit 2 mainly disposed in the indoor space and an outdoor unit 3 mainly disposed in the outdoor space. The indoor unit 2 and the outdoor unit 3 are connected through a refrigerant communication piping, and the structure forms a refrigerant circuit 10 configured to execute a vapor compression refrigeration cycle.

In the refrigerant circuit 10, a compressor 11, a four-way switching valve 12, a convective heat exchanger 13, an expansion valve 15, an outdoor heat exchanger 16 are sequentially connected. Further, a branch pipe 40 is disposed in parallel to the convective heat exchanger 13. An open/close valve 41, a first check valve 42, a radiant heat exchanger 14 and a second check valve 43 are series-connected to the branch pipe 40 while being sequentially aligned from the compressor 11 side. Further, an accumulator 20 is connected to the four-way switching valve 12 and the inlet of the compressor 11.

The four-way switching valve 12 is configured to cause the refrigerant discharged from the compressor 11 to flow towards either the convective heat exchanger 13 or the outdoor heat exchanger 16. During a heating operation, for instance, a control unit is configured to cause the four-way switching valve 12 to select a flow path depicted with a solid line in FIG. 1 for causing the refrigerant to flow towards the convective heat exchanger 13. During a cooling operation, by contrast, the control unit is configured to cause the four-way switching valve 12 to select a flow path depicted with a dotted line in FIG. 1 for causing the refrigerant to flow towards the outdoor heat exchanger 16.

The convective heat exchanger 13 is a type of heat exchanger formed by a plurality of fins and a plurality of heat transfer tubes arranged perpendicularly to the fins. The convective heat exchanger 13 is configured to execute heat exchange between the refrigerant flowing through the heat transfer tubes and the air flowing against the surfaces of the fins. A fan 23 is disposed in the vicinity of the convective heat exchanger 13 for supplying air towards the surfaces of the fins.

The radiant heat exchanger 14 is a type of heat exchanger formed by a plate (hereinafter referred to as a panel) made of aluminum and heat transfer tubes attached to the panel. The radiant heat exchanger 14 is configured to heat the panel by means of the high pressure refrigerant flowing through the heat transfer tubes for causing the panel to emit radiant heat.

The expansion valve 15 is an electronic expansion valve functioning as a decompression mechanism. The expansion valve 15 is connected between the convective heat exchanger 13 and the outdoor heat exchanger 16. The expansion valve 15 is configured to narrow the refrigerant flow path for decompressing the refrigerant. The outdoor heat exchanger 16 is a type of heat exchanger formed by a plurality of fins and a plurality of heat transfer tubes arranged perpendicularly to the fins. The outdoor heat exchanger 16 is configured to execute heat exchange between the refrigerant flowing through the heat transfer tubes and the air flowing against the surfaces of the fins. Further, an outdoor fan 33 is disposed in the vicinity of the outdoor heat exchanger 16 for supplying air towards the surfaces of the fins. The accumulator 20 is configured to accumulate excessive liquid refrigerant and return only gas refrigerant to the compressor 11.

A discharge temperature sensor 111 is attached to a discharge pipe connecting the outlet of the compressor 11 and the four-way switching valve 12. The discharge temperature sensor 111 is configured to detect the temperature of the high pressure refrigerant to be discharged from the compressor 11.

The control unit is configured to control the temperature of the panel of the radiant heat exchanger 14 based on the temperature to be detected by the discharge temperature sensor 111. However, another temperature sensor (hereinafter referred to as a second temperature sensor 114) may be attached in the vicinity of the high pressure refrigerant inlet of the radiant heat exchanger 14 when the temperature to be detected by the discharge temperature sensor 111 and the temperature of the panel are different due to pressure loss caused by a long pipe connecting the open/close valve 41 and the radiant heat exchanger 14. It should be noted that both of the discharge temperature sensor 111 and the second temperature sensor 114 are used in the present exemplary embodiment.

<Internal Structure of Indoor Unit 2>

FIG. 2 is an exploded perspective view of the internal structure of the indoor unit. In FIG. 2, the outer shell of the indoor unit 2 is formed by a frame 210 and a grill 240. In the frame 210, a left plate 212, a right plate 213 and a top plate 214 are respectively fixed to the left end, the right end and the top end of a rectangular opening 211. The frame 210 includes a fan compartment 210 a and an electric component compartment 210 b.

The grill 240 includes an upper blower vent 240 a, a lower blower vent 240 b, an opening 240 c, a left suction vent 240 d and a right suction vent 240 e. The upper blower vent 240 a is positioned on the upper part of the grill 240, whereas the lower blower vent 240 b is positioned on the lower part of the grill 240. The opening 240 c is formed for exposing a panel 14 a to the indoor space. The left suction vent 240 d is positioned on the left face of the grill 240, whereas the right suction vent 240 e is positioned on the right face of the grill 240.

Air is inhaled through the left suction vent 240 d and the right suction vent 240 e in conjunction with activation of the fan 23 and passes through a filter 218 disposed on the upstream of the convective heat exchanger 13 via spaces between the heat insulated rear face of the panel 14 a and suction path forming plates 115 and 116. After passing through the filter 218, the air is directed to the convective heat exchanger 13. Heat exchange is then executed for the air in the convective heat exchanger 13. The heat-exchanged air passes through a circular hole 216 a of a bell mouth 216 and enters the fan 23. The air is then blown out of the fan 23, travels through the fan compartment 210 a towards the upper blower vent 240 a and the lower blower vent 240 b, and is blown out through the upper blower vent 240 a and the lower blower vent 240 b.

The circular hole 216 a of the bell mouth 216 has a diameter slightly less than the vane inner diameter of the fan 23. When passing through the circular hole 216 a, the air enters between the vanes of the fan 23 and is compressed by the vanes of the fan 23. The compressed air is blown out in the outer peripheral direction of the fan 23.

A motor support plate 215 is disposed and fixed between the top and the bottom of the fan compartment 210 a for supporting a driving motor 23 a of the fan 23. The driving motor 23 a is fixed to the motor support plate 215 by means of screws 23 b. The bell mouth 216 then closes the fan compartment 210 a. An electric component box 24 is held in the electric component compartment 210 b. The electric component box 24 accommodates the control unit embedded with a CPU, a memory and etc.

A heat exchanger assembly 220 is an integrated structure of the convective heat exchanger 13 and the radiant heat exchanger 14. A drain pan assembly 217 is disposed below the convective heat exchanger 13. During a cooling operation, for instance, moisture contained in the air is condensed on the surface of the convective heat exchanger 13 when the air passes through the conductive heat exchanger 13. The drain pan assembly 217 receives such condensed water falling from the convective heat exchanger 13.

It should be noted that a blower vent assembly 250 is attached to the upper blower vent 240 a. The blower vent assembly 250 includes a louver for changing an air blowing-out direction. Further, a left frame bar 241, a right frame bar 242 and an upper frame bar 243 are respectively attached to the left edge, the right edge, and the upper edge of the opening 240 c of the grill 240.

FIG. 3 is a side view of the heat exchanger assembly. In the heat exchanger assembly 220 of FIG. 3, the convective heat exchanger 13 and the radiant heat exchanger 14 are fixed to each other by means of attachment plates 221. Each attachment plate 221 is a sheet-metal member extended from a frame 14 c of the radiant heat exchanger 14 in an opposite direction to the panel 14 a. Each attachment plate 221 includes through holes 221 a.

The convective heat exchanger 13 includes a pair of tube plates 13 c in the vicinity of the both ends of each heat transfer tube 13 b. Each tube plate 13 c includes screw holes to be matched with the through holes 221 a of the attachment plates 221. The convective heat exchanger 13 and the attachment plates 221 are fixed by means of screws via the through holes 221 a.

FIG. 4 is a cross-sectional view of the radiant heat exchanger for illustrating an exemplary attachment structure of the panel and the heat transfer tubes. In FIG. 4, attachment brackets 14 e are opposed to the panel 14 a while heat transfer tubes 14 b are interposed therebetween. Specifically, the attachment brackets 14 e are fixed to bracket receivers 14 d having preliminarily fixed to the panel 14 a by means of attachment screws 14 f. Each bracket receiver 14 d includes a screw hole 14 da that one of the attachment screws 14 f is screwed. Each attachment bracket 14 e includes a flat plate portion 14 ea, a bulged portion 14 eb and flanged portions 14 ec. The flat plate portion 14 ea is closely attached to the rear face, opposite to the radiant face, of the panel 14 a. The bulged portion 14 eb is bulged from the flat plate portion 14 ea for forming a U-shaped groove that one of the heat transfer tubes 14 b is fitted. The flanged portions 14 ec, bulged from the both ends of the flat plate portion 14 ea, are fixed to the bracket receivers 14 d. Each flanged portion 14 ec includes a through hole 14 ed to be matched with the screw hole 14 da of each bracket receiver 14 d.

The heat transfer tubes 14 b are firstly disposed on the rear face of the panel 14 a. Subsequently, the attachment brackets 14 e are respectively disposed while the through holes 14 ed thereof are faced to the screw holes 14 da of the bracket receivers 14 d. Under the condition, the flanged portions 14 ec of the attachment brackets 14 e are respectively fixed to the bracket receivers 14 d by means of the attachment screws 14 f. Consequently, the attachment brackets 14 e and the heat transfer tubes 14 b are pressed onto the panel 14 a. Heat can be thereby reliably transferred from the attachment brackets 14 e and the heat transfer tubes 14 b to the panel 14 a.

<Actions of Air Conditioner 1>

The air conditioner 1 is configured to cause the four-way switching valve 12 to change the refrigerant flow path for switching between a cooling operation and a heating operation. First, an exemplary case will be explained that the refrigerant circuit functions as a circuit for a heating operation.

(Heating Operation)

During a heating operation, the flow path depicted with the solid line in FIG. 1 is selected in the four-way switching valve 12. Accordingly, the high pressure gas refrigerant, discharged from the compressor 11, branches into and flows through the branch pipe 40 and the convective heat exchanger 13. The branch point of the refrigerant flow is hereinafter referred to as a point A. The gas refrigerant, flowing into the branch pipe 40 at the point A, sequentially flows through the open/close valve 41, the first check valve 42, the radiant heat exchanger 14 and the second check valve 43, and then joins the refrigerant flowing from the convective heat exchanger 13. The confluence of the refrigerant flows is hereinafter referred to as a point B.

The attachment brackets 14 e and the heat transfer tubes 14 b are closely attached to the panel 14 a (see FIG. 4). The heat of the gas refrigerant is thereby transferred to the panel 14 a through the heat transfer tubes 14 b. Accordingly, the panel 14 a increases its temperature. The panel 14 a with increased temperature herein emits radiant heat. Therefore, air and objects, positioned ahead the panel 14 a, are heated by the radiant heat. In the radiant heat exchanger 14, the gas refrigerant is partially condensed by means of heat exchange with the panel 14 a. Therefore, the liquid refrigerant and the gas refrigerant herein coexist in the radiant heat exchanger 14.

The gas refrigerant, flowing into the convective heat exchanger 13 at the point A, is condensed as a result of heat exchange with the air flowing against the outside of the convective heat exchanger 13. On the other hand, the air increases its temperature in the convective heat exchanger 13 and is blown out to the indoor space for heating the indoor space.

Further, the liquid refrigerant, flowing out of the convective heat exchanger 13, joins the refrigerant flowing out of the radiant heat exchanger 14 at the point B. The joined refrigerant subsequently flows towards the outdoor heat exchanger 16. On the way to the outdoor heat exchanger 16, the joined refrigerant is decompressed in the expansion valve 15. The decompressed refrigerant then flows into the outdoor heat exchanger 16. In the outdoor heat exchanger 16, the refrigerant evaporates and changes into the gas refrigerant as a result of heat exchange with the air flowing against the outside of the outdoor heat exchanger 16.

After flowing out of the outdoor heat exchanger 16, the gas refrigerant is returned to the compressor 11 via the four-way switching valve 12 and the accumulator 20. The air conditioner 1 is thus configured to execute a heating operation using the radiant heat exchanger 14 and the convective heat exchanger 13.

FIG. 5 is a chart representing the relation between temperature to be detected by the second temperature sensor and actions of the open/close valve during a heating operation. In FIG. 5, the open/close valve 41 is configured to switch the flow path from an opened state to a closed state when the temperature detected by the second temperature sensor 114 exceeds a predetermined temperature (herein set as 70 degrees Celsius). In other words, the open/close valve 41 is configured to switch a state of the refrigerant flowing into the radiant heat exchanger 14 to a state of the refrigerant flowing into only the convective heat exchanger 13 without flowing into the radiant heat exchanger 14.

When a preliminarily set switching period of time T1 elapses, the open/close valve 41 is configured to switch the flow path back to the opened state from the closed state. Accordingly, the air conditioner 1 is returned to the heating operation using the radiant heat exchanger 14.

During a heating operation only using the convective heat exchanger 13, the liquid refrigerant and the gas refrigerant remain residing between the open/close valve 41 and the point B. When the liquid refrigerant spontaneously evaporates under the condition, the internal pressure is increased between the open/close valve 41 and the point B. In the present exemplary embodiment, however, the first check valve 42 is disposed between the radiant heat exchanger 14 and the open/close valve 41. Even when the liquid refrigerant spontaneously evaporates and the internal pressure is increased, the pressure within the radiant heat exchanger 14 does not affect the open/close valve 41. Further, less liquid refrigerant exists between the open/close valve 41 and the first check valve 42. Even when the liquid refrigerant existing therein spontaneously evaporates and the internal pressure is increased, the internal pressure is not increased enough to push and open the open/close valve 41. Therefore, occurrence of chattering is herein prevented.

When the panel 14 a of the radiant heat exchanger 14 sufficiently reduces its temperature during a heating operation only using the convective heat exchanger 13, the branch pipe 40 is opened by the open/close valve 41 and the heating operation is again executed by the radiant heat exchanger 14 and the convective heat exchanger 13.

(Cooling Operation)

Next, an exemplary case will be explained that the refrigerant circuit functions as a circuit for a cooling operation. During a cooling operation, the flow path depicted with the dotted line in FIG. 1 is selected in the four-way switching valve 12. Accordingly, the high pressure gas refrigerant, discharged from the compressor 11, flows towards the outdoor heat exchanger 16. The gas refrigerant is condensed as a result of heat exchange with the air flowing against the outside of the outdoor heat exchanger 16. The liquid refrigerant, flowing out of the outdoor heat exchanger 16, flows towards the convective heat exchanger 13. On the way to the convective heat exchanger 13, the liquid refrigerant is decompressed in the expansion valve 15. The decompressed refrigerant then flows into the convective heat exchanger 13. It should be noted that the liquid and gas refrigerant is blocked from flowing into the branch pipe 40 at the point B by the second check valve 43 before flowing into the convective heat exchanger 13.

In the convective heat exchanger 13, the liquid refrigerant evaporates and changes into the gas refrigerant as a result of heat exchange with the air flowing against the outside of the convective heat exchanger 13. On the other hand, the air reduces its temperature in the convective heat exchanger 13 and is blown out to the indoor space for cooling the indoor space. The gas refrigerant flows out of the convective heat exchanger 13 and flows towards the four-way switching valve 12 via the point A. The gas refrigerant is then returned to the compressor 11 via the four-way switching valve 12 and the accumulator 20.

<Features>

According to the air conditioner 1, as described above, the branch pipe 40 is configured to be closed by the open/close valve 41 for blocking the high pressure refrigerant from flowing into the radiant heat exchanger 14 when the temperature of the panel 14 a of the radiant heat exchanger 14 reaches the upper limit of its permissive temperature during a heating operation using the radiant heat exchanger 14. As a result, reduction in the temperature of the refrigerant is accelerated within the radiant heat exchanger 14 and reduction in the temperature of the panel 14 a is also accelerated. Therefore, the air conditioner 1 can be returned to the heating operation using the radiant heat exchanger 14.

Further, the first check valve 42 is disposed between the radiant heat exchanger 14 and the open/close valve 41. Therefore, less liquid refrigerant exists between the open/close valve 41 and the first check valve 42 when the open/close valve 41 is closed. Even when the liquid refrigerant spontaneously evaporates and the internal pressure is increased, the internal pressure is not increased enough to push and open the open/close valve 41. Therefore, occurrence of chattering is prevented.

<Modification>

In the aforementioned exemplary embodiment, the open/close valve 41 is employed for closing and opening the branch pipe 40. However, an opening degree regulating valve may be used instead of the open/close valve 41. The opening degree regulating valve herein has a function of blocking the flow path of the branch pipe 40 and a function of regulating the opening degree of the flow path of the branch pipe 40.

With the opening degree regulating valve, the temperature of the panel 14 a of the radiant heat exchanger 14 is increased or reduced by regulating the opening degree of the flow path. Further, the flow path of the refrigerant is configured to be blocked when the temperature of the panel 14 a reaches its upper limit. Therefore, the opening degree regulating valve can enhance convenience and safety of the air conditioner 1.

<Other Modifications>

The attachment structure of the panel 14 a and the heat transfer tubes 14 b in the radiant heat exchanger 14 is not limited to that illustrated in FIG. 4. Other attachment structures will be hereinafter explained with reference to FIGS. 6 to 10. It should be noted that the face, opposite to the radiant face, of the panel 14 a will be hereinafter referred to as a rear face for the sake of easy explanation.

FIG. 6 is a cross-sectional view of the radiant heat exchanger for illustrating a second attachment structure of the panel and the heat transfer tubes. In FIG. 6, each of attachment panels 141 includes a flat plate portion 141 a and bulged portions 141 b. The flat plate portion 141 a is joined to the rear face of the panel 14 a, whereas the bulged portions 141 b are bulged from the flat plate portion 141 a. Each bulged portion 141 b is bulged higher than the diameter of each heat transfer tube 14 b. Each bulged portion 141 b includes a U-shaped groove 141 c that one of the heat transfer tubes 14 b is fitted. Each heat transfer tube 14 b is fitted into corresponding one of the U-shaped grooves 141 c and then the edges of the opening of the U-shaped groove 141 c are pressed and swaged onto the outer peripheral surface of each heat transfer tube 14 b.

FIG. 7 is a cross-sectional view of the radiant heat exchanger for illustrating a third attachment structure of the panel and the heat transfer tubes. In FIG. 7, the panel 14 a and the heat transfer tubes 14 b are jointed by means of brazing. In this case, a filler material 140 is filled with corners (i.e., clearances) produced in contact portions between the panel 14 a and the heat transfer tubes 14 b. Therefore, heat can be efficiently transferred from the heat transfer tubes 14 b to the panel 14 a.

FIG. 8 is a cross-sectional view of the radiant heat exchanger for illustrating a fourth attachment structure of the panel and the heat transfer tubes. In FIG. 8, each of first attachment brackets 341 includes a flat plate portion 341 a and a bulged portion 341 b. The flat plate portion 341 a is joined to the rear face of the panel 14 a, whereas the bulged portion 341 b is bulged from the flat plate portion 341 a. The flat plate portion 341 a is closely joined to the rear face of the panel 14 a by means of either spot welding or brazing. The bulged portion 341 b is bulged at a height roughly the same as the diameter of each heat transfer tube 14 b. The bulged portion 341 b includes a U-shaped groove 341 c that one of the heat transfer tubes 14 b is fitted. Further, the bulged portion 341 b includes screw holes 341 d on the both sides of the U-shaped groove 341 c.

Each of second attachment brackets 342 includes through holes 342 a to be matched with the screw holes 341 d of corresponding one of the first attachment brackets 341. The second attachment brackets 342 are respectively fixed to the first attachment brackets 341 by means of screws 343 for covering the heat transfer tubes 14 b respectively fitted into the U-shaped grooves 341 c. The respective heat transfer tubes 14 b are herein slightly protruded from the U-shaped grooves 341 c. Therefore, the heat transfer tubes 14 b are respectively pressed and closely fitted to the U-shaped grooves 341 c when the second attachment brackets 342 are respectively fixed to the first attachment brackets 341 by means of screws.

FIG. 9 is a cross-sectional view of the radiant heat exchanger for illustrating a fifth attachment structure of the panel and the heat transfer tubes. In FIG. 9, each of presser brackets 441 includes a flat plate portion 441 a and a U-shaped groove 441 b. The flat plate portion 441 a is joined to the rear face of the panel 14 a. The U-shaped groove 441 b is opposed to the rear face of the panel 14 a while one of the heat transfer tubes 14 b is interposed therebetween. Specifically, the heat transfer tubes 14 b are disposed on the rear face of the panel 14 a and are then respectively covered with the U-shaped grooves 441 b of the presser brackets 441. Under the condition, the flat plate portions 441 a of the presser brackets 441 and the rear face of the panel 14 a are joined by means of either spot welding or brazing.

FIG. 10 is a cross-sectional view of the radiant heat exchanger for illustrating a sixth attachment structure of the panel and the heat transfer tubes. In FIG. 10, the panel 14 a includes bulged portions 541 on the rear face thereof. The bulged portions 541 are arranged in the positions where the heat transfer tubes 14 b are disposed. Each bulged portion 541 includes a U-shaped groove 541 a that one of the heat transfer tubes 14 b is fitted. The U-shaped groove 541 a has a predetermined depth for allowing the outer peripheral surface of each heat transfer tube 14 b to be slightly protruded therefrom when fitted therein. Further, each bulged portion 541 includes screw holes 541 b on the both sides of the U-shaped groove 541 a.

Each of presser brackets 542 includes through holes 542 a to be matched with the screw holes 541 b of corresponding one of the bulged portions 541. The presser brackets 542 are respectively fixed to the bulged portions 541 by means of screws 543 for covering the outer peripheral surfaces of the heat transfer tubes 14 b respectively slightly protruded from the bulged portions 541.

INDUSTRIAL APPLICABILITY

As described above, the present invention is useful for a heating machine using a radiant heat exchanger.

REFERENCE SIGNS LIST

-   1 Air conditioner -   10 Refrigerant circuit -   13 Convective heat exchanger -   14 Radiant heat exchanger -   41 Open/close valve -   42 First check valve

CITATION LIST Patent Literature

-   PTL 1: Japan Laid-open Patent Application Publication No.     JP-A-H07-055234 

1. An air conditioner configured to execute a heating operation using at least a high pressure refrigerant, the air conditioner comprising: a refrigerant circuit configured to execute a vapor compression refrigeration cycle, the refrigerant circuit including: a convective heat exchanger configured to execute heat exchange between the high pressure refrigerant flowing through an inside thereof and an air flowing towards an outside thereof; a radiant heat exchanger configured to heat a predetermined member by using the high pressure refrigerant flowing through the inside thereof to cause the predetermined member to emit a radiant heat; an open/close valve disposed upstream of the radiant heat exchanger in order to block a flow path of the high pressure refrigerant flowing towards the radiant heat exchanger during the heating operation; and a check valve disposed between the radiant heat exchanger and the open/close valve.
 2. The air conditioner recited in claim 1, wherein the open/close valve is an opening degree regulating valve arranged and configured to block the flow path and to regulate an opening degree of the flow path.
 3. The air conditioner recited in claim 1, wherein the open/close valve is arranged and configured to block the flow path when a temperature of the predetermined member reaches an upper limit of a permissive temperature.
 4. The air conditioner recited in claim 2, wherein the open/close valve is further arranged and configured to block the flow path when a temperature of the predetermined member reaches an upper limit of a permissive temperature. 